There is a technology in which an object is recognized according to a similarity degree calculated by extracting an appearance feature amount of the object from the image data of the object photographed by an image capturing section and comparing the extracted appearance feature amount with the feature amount data of a reference image of each object pre-registered in a recognition dictionary file. Such a technology is called as a general object recognition, and various recognition technologies are disclosed in the following document.
Keiji Yanai “Current status and future direction of general object recognition”, Journal of Information Processing Society, Vol. 48, No. SIG16 [Search on Heisei 22 August 10], Internet <URL:http://mm.cs.uec.ac.jp/IPSJ-TCVIM-Yanai.pdf>
In addition, the technology carrying out the general object recognition by area division of the image for each object is described in the following document.
Jamie Shotton etc, “Semantic Texton Forests for Image Categorization and Segmentation”, [Search on Heisei 22 August 10], Internet <URL:http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.145.3036&rep=repl&type=pdf>
In recent years, for example, the general object recognition technology described above is proposed to be applied to a recognition apparatus for recognizing a commodity, especially a commodity on which a barcode is not applied, such as vegetables, fruits and the like purchased by a customer in a checkout system (POS system) of a retail store. In this case, an operator (a shop clerk or a customer) holds the recognition target commodity over the image capturing section. In this way, in the commodity recognition apparatus, the commodity is recognized from a captured image and the information (for example, a commodity name) indicating the recognition result is displayed on a display section.
However, the commodity is not always recognized. For example, there is a case in which the commodity is not recognized because the commodity is shield by the hand of the operator. Alternatively, there is a case in which the commodity is not recognized because the similar feature amount data is not registered in the recognition dictionary file. Further, there is a case in which the commodity is not recognized because the commodity recognition program is frozen.
The commodity recognition apparatus has no reaction in a case in which the commodity is not recognized. As a result, it is difficult to determine the reason why the commodity is not recognized, and most operators feel stress because they tried to change the position and the direction to hold the commodity.